"This first test flight brings aviation closer than ever to the reality of regular, sustained hypersonic flight," said Curtis Berger, director of Hypersonic Programs, Pratt & Whitney Rocketdyne. "We are very proud to be part of the team that made this possible."

The X-51A program is a collaborative effort of the U.S. Air Force Research Laboratory, the Defense Advanced Research Projects Agency (DARPA), Boeing and Pratt & Whitney Rocketdyne.

Charlie Brink, X-51A program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, said: "We are ecstatic to have accomplished many of the test objectives on the X-51A's very first hypersonic mission. We equate this leap in engine technology as equivalent to the post-World War II jump from propellers to jet engines."

"The X-51A program is a critical element in our progression to practical hypersonic propulsion, providing a greater understanding of hypersonic propulsion performance, control and structural durability," said George Thum, X-51A program manager, Pratt & Whitney Rocketdyne.

During its first flight, the unmanned WaveRider vehicle was carried beneath a U.S. Air Force B-52 and dropped from an altitude of about 50,000 feet over the Pacific Ocean off southern California. A solid rocket booster fired and propelled the cruiser to greater than Mach 4.5, creating the supersonic environment necessary to operate the engine.

The booster was then jettisoned and the Pratt & Whitney Rocketdyne SJY61 scramjet engine ignited, initially on gaseous ethylene fuel. Next the engine transitioned to JP-7 jet fuel, the same fuel once carried by the SR-71 Blackbird before its retirement.

Pratt & Whitney Rocketdyne is a part of Pratt & Whitney and a preferred provider of high-value propulsion, power, energy and innovative system solutions used in a wide variety of government and commercial applications, including the main engines for the space shuttle, Atlas and Delta launch vehicles, missile defense systems and advanced hypersonic engines. For more information about Pratt & Whitney Rocketdyne and to view a video animation of the planned X-51A first flight, go to http://www.pwrhypersonics.com.

Pratt & Whitney is a world leader in the design, manufacture and service of aircraft engines, space propulsion systems and industrial gas turbines. United Technologies, based in Hartford, Conn., is a diversified company providing high technology products and services to the global aerospace and commercial building industries.